SEEDING DEPTH AND PACKING WHEEL PRESSURE EFFECTS ON OILSEED RAPE EMERGENCE

Oilseed rape (Brassica napus L.), including industrial (rapeseed) and canola quality cultivars, offers potential for doublecropping in the s outheastern USA. Early attempts at commercialization of this crop in t he Southeast have frequently encountered difficulties in establishing stands. This 3-yr project (1986-1989) was undertaken to evaluate the e ffects of seeding depth and planter configuration (i.e., packing wheel pressure) on emergence of oilseed rape. The two field sites used for this study contained Lakeland sand (thermic, coated Typic Quartzipsamm ent) and Tifton loamy sand (fine, loamy, siliceous Plinthic Paleudult) soil types, respectively. Treatment factors were planter configuratio n, seeding depth, and cultivar. The experimental design was a randomiz ed complete block with four replications. Planter configurations consi sted of a Tye drill with both high and low pressure settings on the pa cking wheels and an Amazone drill with no packing wheel pressure (seco nd season only). Seeding depths ranged from 0.25 to 2 in. Cultivars we re 'Cascade' and 'Westar' for all three seasons and 'Bridger' during t he last two seasons. Results showed better crop establishment when pla nted shallow (0.25-0.5 in.) than deep (1.5-2 in.). High packing wheel pressure at planting had a positive effect on stand when the crop was sown on sandy soil with little potential for surface crusting. For exa mple, on the cultivar Cascade, the increased packing wheel pressure in creased the stand density by 15% over the low packing wheel pressure i n the second season. For Westar in the same season and at the 1.5 in. depth, the stand density increased nearly 40% when packing wheel press ure increased. However, on loamy sand soils, which have a greater pote ntial for crusting, better emergence occurred when low packing wheel p ressure was applied.